This invention relates to electrohydraulic stroking devices and in particular to a rotary actuator for stroking a manual servo valve on a hydraulic pump.
Present actuators use an electrical stepping motor coupled with feedback potentiometers to control hydraulic pump flow. Manual control is unavailable when an electrical stepping motor actuator is utilized. Mechanical positioning of a remote control stick provides electrical signals for positioning and stepping motor and hence the actuator to a discrete number of positions. In the event electrical power is lost centering of the actuators is provided by springs. When manual centering is desired in present actuators a spring centering mechanism is utilized which normally does not result in positive centering since the springs deteriorate with use. Additionally, the centering force increases as movement from the neutral position occurs therefore affecting dynamic performance.